Flat panel cathode ray tube particularly adapted for radar displays

ABSTRACT

A flat panel cathode ray display in which a phosphor screen is selectively excited from an area cathode through a multichannel flat panel electron multiplier array. Electrons are permitted to flow substantially only through one hole of the multichannel array at a time as controlled by separate radial and circumferential scan components. The holes of the multichannel array are arranged in substantially concentric circles and also in radial lines, and a system of conductive strips provides a gating potential distribution means to effect sequencing of the required pattern of electron flow through the multichannel array holes. The aforementioned holes are through the bottom of a panshaped insulating body, the extensions of the radial and circular conductive strips overlapping the holes being drawn up over the insides of the pan-shaped body side flanges or walls. Separate electron beam scanning means for the conductive extensions of the circular and radial strips are provided by electron beam scanning means around selected portions of the inside surface of the side flange. Secondary emissive material on the individual conductive extensions provides a switching or gating effect during scanning electron beam impingement.

[ Nov. 6, 1973 ABSTRACT FLAT PANEL CATHODE RAY TUBE PARTICULARLY ADAPTED FOR RADAR A flat panel cathode ray display in which a phosphor DISPLAYS screen is selectively excited from an area cathode Inventor:

Hemmo R. Alting-Mees, Granada through a multichannel flat panel electron multiplier Hills, Calif. array. Electrons are permitted to flow substantially only through one hole of the multichannel array at a International Telephone and Asslgnee- Telegraph corporad New York time as controlled by separate radial and circumferen- N Y tial scan components. The holes. of the multichannel array are arranged in substantially concentric circles and also in radial lines, and a system of conductive strips provides a gating potential distribution means to [22] Filed: Dec. 2, 1971 |2l| Appl. No.: 204,233

effect sequencing of the required pattern of electron flow through the multichannel array holes. The afore- ,3]3/92 R, mentioned holes are through the bottom of a pan- I52] U.S. 313/68 R, 313/70 R 315/]3 R shaped insulating body, the extensions of the radial and H01 j 31/12 [51] llnt. HOlj 29/50, circular conductive strips overlapping the holes being [58] Field of Search 313/68 R, 92 R, 70 R, drawn up over the insides of the pan-shaped body side flanges or walls. Separate electron beam scanning means for the conductive extensions of the circular and [56] References Cited radial strips are provided by electron beam scanning UNITED STATES PATENTS means around selected portions of the inside surface of the side flange. Secondary emissive material on the individual conductive extensions provides a switching or gating effect during scanning electron beam impingement.

R 3 1 5 1 3 n a O m u u n 9 mm 1 h mam u m VMRDD 91 011 56677 99999 11111 l/l/l 6207 1 1 69258 7 62 3 02622 97092 89456 8 Claims, 7 Drawing Figures Primary Examiner-Nathan Kaufman Assistant Examiner-Siegfried H. Grimm Att0rney-C. Cornell Remsen, Jr. et al.

FLAT PANEL CATHODE RAY TUBE PARTICULARLY ADAPTED FOR RADAR DISPLAYS BACKGROUND OF THE INVENTION 1. Field of The Invention The invention relates to cathode ray electronic displays and more particularly, to an arrangement for controlling the potential of a multi-channel electron multiplier array hole pattern in a cathode ray tube display particularly adapted for polar presentation.

2. Description of The Prior Art In the prior art, displays were commonly provided for radar indicators by means of elongated funnel-shaped cathode ray tubes having phosphor screens at their enlarged ends and an electron gun located in an elongated neck some distance (usually substantially more than a screen diameter) from the screen itself within an evacuated envelope. The tube neck between the electron gun and the flared portion of the envelope generally contained electrostatic focusing and electrostatic deflection plates or was surrounded by magnetic components which effected beam focusing and deflection magnetically.

The mechanical construction of devices which included such cathode ray tubes, was difficult and usually resulted in cumbersome packaging arrangements because of the large size and awkward form factor of such cathode ray tubes.

In the more recent art, the capabilities of the socalled multichannel electron multiplier array have been exploited to provide flat (neckless) cathode ray tubes. In U.S. Pat. No. 3,541,254, a patent assigned to the assignee of the present invention, a technique and structure is disclosed for controlling the multichannel electron multiplier array so that it admits electrons selectively from an area cathode to a phosphor screen in accordance with a switching pattern applied by means of a lattice of conductive strips uniquely overlapping but not covering the microchannels or holes thereof. In that device, a large number of individual connections to the correspondingly large number of conductive strips in the two coordinates of scan were required. Scanning was effected in accordance with external electronic switching and gating circuitry.

In US. Pat. application, Ser. No. 138,088 filed Apr. 28, 1971, entitled Electron Tube Voltage Control Device" (a patent application assigned to the assignee of the present invention), the general concept of scan by means of a multichannel electron multiplier array was applied but two coordinates of scan were effected by means of a beam switching arrangement whereby the electrical terminals or connections of the plural conductive strips in the two planes of scan were excited in sequence by means of a scanning electron beam or beams impinging upon conductive extensions of themdividual conductive strips. These extensions were provided with a layer of secondary emissive material which responded to the scanning beam by throwing off a much greater number of electrons than impinged upon it from the scanning beam. The result was positive excursion of the corresponding conductive strip during dwell of the electron beam. Thus, wherever strips in the two orthogonal scanning directions thus contemporaneously driven positively crossed in the matrix of strips, a hole through the multichannel electron multiplier array at that particular location was enabled or activated and permitted to pass electrons from the area cathode through to the phosphor screen.

A multichannel array X-Y gating matrix for a rectangular scan arrangement such as shown in the aforementioned US. Pat. No 3,541 ,254 involves the use of plural gating strips numbering on the order of 2,000 and evaporated onto a glass or ceramic plate typical of those devices. Accordingly, it will be readily understood that the present disclosure of a polar scan arrangement would require a comparable number of external contacts were it not for the use of the electron gun strip excitation technique incorporated into the present devlce.

The manner in which the technology of U.S. Pat. No. 3,541,254 and the aforementioned U.S. Pat. application Ser. No. 138,088, filed Apr. 28, 1971, is applied and extended in producing the novel structure and operation of the present invention will be evident as this description proceeds.

SUMMARY OF THE INVENTION The present invention involves the use of a glass or ceramic plate formed preferably in the shape of a pan or dish. This pamshaped plate may be thought of as having axially an extending side wall or flange and a relatively flat bottom plate, the relatively large plurality of microchannels or holes extend through the said bottom plate. Two sets of conductive strip electrodes are supplied, one set in the form of plural discrete concentric circles and the other set in the form of plural discrete radially extending strips. A conductive extension of each strip is extended and brought axially over the inside of the side flange, these extensions being grouped together in corresponding sets. Two axially separated scanning electron sources are provided, one providing a relatively rapid rate of scan and the other a relatively slow rate of scan as would be typical of the azimuth scan of a plan position (PPI), for example.

The conductive extensions aforementioned are each faced with a layer of highly secondary emissive material. The two electronic scanning arrangements then are adapted to separately scan groups of the aforementioned extensions corresponding to rho (p) and theta (0) components of a polar plot (range and bearing or azimuth in the context of a PPI radar). As the corresponding beam strikes the photo emissive material on each of the conductive extensions, the secondary emission which takes place causes that conductive extension to be driven in a positive direction or effectively gated positively. The same effect is achieved by the other scanning gun in respect to the other set of strip electrodes. Thus, as the two scans take place, substantially only one hole corresponding to the crossover of conductive strip electrodes at a discrete angle 6 and an electrode from the other set representing a discrete distance p (the equivalent of range and azimuth in a PPI instrumentation). Thus, typically, the concentric ring electrodes would be scanned from the center out at the relatively rapid rate of a range time basis scan. The radial strip electrodes, on the other hand, are scanned sequentially around the entire 360 of the said concentric ring electrodes (for the PPI case) or in the case of a polar sector type scan, over that portion of the full circle which is of interest.

The general objective of the present invention was the achievement of the flat panel cathode ray tube for polar scan of the type commonly used in radar systems.

The advantage of much simplified packaging because of the absence of the customary cathode ray tube neck will be immediately apparent to those skilled in the art. Other advantages will be evident as this description proceeds. For example, it is to be noted that the device is much less sensitive to stray magnetic fields than is the customary cathode ray tube because of the very short electron travel between the microchannel plate and the phosphor screen.

BRIEF DESCRIPTION OF THE DRAWINGS The drawings which are to be considered illustrative and typical only, are as follows:

FIG. I is a perspective of the multichannel array with pan-shaped body and circular and radial strip electrodes shown for sector scan use.

FIG. 2 is a sideview of FIG. 1.

FIG. 3 is a sectional view taken along lines 33 in FIG. I, the section line passing through a selected ra' dial strip electrode.

FIG. 4 is a side, edge-on, view of a completed assembly in accordance with the invention representing the essential and some optional elements.

FIG. 5 is a pictorial of an alternative beam-gating arrangement also shown in FIG. 4, for effecting scan switching of the concentric ring electrodes.

FIG. 6 is a detail of the electron scan terminal block of FIGS. 4 and 5.

FIG. 7 illustrates an alternative concentric ring strip electrode connection arrangement adapted for 360 0 (bearing) scan.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. I, the pan-shaped glass or ceramic pan-shaped plate with axially extending side flange is illustrated generally at 10. The axial centerline I1 is indicated for convenience in understanding what is meant when any element is said to be axially extending or axially separated or displaced, i.e., axial in that context being along line 11 or along a line parallel thereto. Thus, it is appropriate to speak of the pan side as being an axially extending side flange a. Normally, but not necessarily, the inside plate containing the radial and concentric circuit conductive strip elements would be flat and itself circular, and therefore, the axially extending side flange would be (but not as an absolute requirement) in the form of a cylindrical shell, preferably integral with the inside bottom plate, but at least attached thereto.

, It will be realized that the'showings of all of the figures of this case are exaggerated dimensionally for clarity. The actual number of microchannels or holes in the bottom plate 1017 may number in the tens of thousands, and the number of such conductive'strip electrodes in the radial and circular sets would number in the thousands as hereinbefore estimated. The holes, or microchannels themselves are on the order of a comparatively few mils in diameter. It is felt unnecessary to review the methods by which these conductive strip electrodes and the microchannel plate 10b are fabricated. These methods and processes are well known in this art, as are the materials used. A very satisfactory material for the microchannel plate 10!) is the so-called FOTOCERAM material.

For each of the radially extending conductive strip electrodes, typically l2, l3 and 14, there is a correspending extension typically 15, 16 and 17, respectively, running axially outward along the inside surface of the side flange 10a. These extension strips are continued along the planar annular edge of 10a in the form of resistive strips 18, 19 and 20, respectively.

Considering now the concentric circular strip electrodes, of which 21, 22 and 23 are typical, the conductive extensions comprise 24 and 27 for circle 21; 25 and 28 for circle 22; and 26 and 29 for circle 23. Similarly, the corresponding resistive strip 30, 31 and 32 (typically) will be noted.

Referring now to FIG. 2, a sideview further clarifies the location of conductive collector strips 33 and 34. The resistive strips 36 generally depict the strips of the group of which 18, 19 and 20 (corresponding to radial strip electrodes) are a part. The resistive strip 35, similarly, is a sideview of one of the group, including 30, 31 and 32, corresponding to concentric circular elements. Both the 35 and 36 strip thicknesses are considerably exaggerated in FIG. 2 for clarity. It is to be understood that these are relatively thin films as is the overall array output side conductive film 37. The strips 33 and 34, in effect, collect their respective charging resistor leads (resistive strips) as aforementioned and provide common terminals for return circuit through a small positive voltage to the corresponding gun cathode.

Referring now also to FIG. 3, it will be realized that the sectional view, taken through 33, on FIG. 1, which FIG. 3 represents, has been rotated. Its physical relationship with FIGS. 1 and 2 will be understood from the location of the (of exaggerated thickness) conductive layer 37 and the conductive layers 33 and 34; also of the resistive strips 35 and 36, representative of the two groups of resistive strips as hereinbefore pointed out.

It being assumed that the section line 33 of FIG. 1 passed lengthwise through the radial conductive strip electrode 12, it follows that the strip 12 would appear as shown in FIG. 3. Accordingly, three of the arbitrarily selected microchannels or holes, 38, 39 and 40, appear in both FIGS. 1 and 3, at the crossover of the radial electrode 12, and electrodes 21, 22 and 23 for holes 38, 39 and 40, respectively. FIG. 3 is intended to correspond to FIG. 1, and, accordingly, the typical insulator strips 41 and 42 are of different thickness, depending upon presence or absence of a radial electrode at the particular location essentially diametrically opposite to 12. In the particular instance, no such radial electrode exists at that opposite position, however, in a 360 version which will be discussed later, a radial strip electrode would occupy a complimentary position of FIG. 3, and therefore, insulators 41 and 42 would be essentially the same thickness.

It is particularly important to note that the microchannels or holes pass through both sets of strips the insulating separators, such as 41 and 42, the plate body 10b, and finally, through the conductive output side layer 37. Stated otherwise, corresponding holes in these elements are in registration when they are assembled in accordance with the foregoing.

Referring now also to FIGS. 4 and 5, it will be possible to discuss the electronic scanning guns in more detail. In FIG. 4, a complete assembly of minimum functional elements is shown enclosed in an evacuated envelope 63 (typically of glass). An optional element 61 is also included and will be discussed hereinafter.

In the particular embodiment of FIG. 4, an electron gun 53 produces a ribbon beam 64 which is very narrow in the plane of FIG. 4 and somewhat wider in the orthogonal coordinate. A set of deflection plates 52, controlled by an electronic scan circuit 50, via lead 49,

provides scanning of the said ribbon beam 64 in a plane normal to the plane of FIG. 4 and across the face of the scan terminal block 54. The scan control signal on lead 49 would normally be in the nature of a sawtooth voltage providing the time base for the polar display.

The ordinarily slower scan rate in bearing is typically provided by a rotating second ribbon beam gun 46, represented as being mounted to rotate in a plane normal to the showing of FIG. 4 about a shaft or axle 65. The ribbon beam 45 produced by gun 46, would be of comparable size (as is 64) in the plane of FIG. 4 and in the orthogonal plane, however, in view of the relatively much slower azimuth scan, adequate gating of the radial conductive strip electrodes can be effected with lower beam current density than is the case for the scanning ribbon beam 64. Connection to the rotating gun 46 is relatively easily accomplished by means of a rotating or slip-ring joint at 66, to lead 49. Actually, lead 48 and slip-ring 66 may be thought of as more than one individual connection, and, in fact, whatever connections are required to operate and focus the electron gun 46 are readily provided in this way.

The secondary emissive layers 43 and 44 will be recognized from FIG. 3. The form factor or pan depth exhibited in FIG. 3 is not intended to be sealer, since it will be apparent from FIG. 4 that the introduction of the scanning hardware requires that the pan-shaped body be sufficiently deep to accommodate the required components. Nevertheless, this axial depth of the device of FIG. 4 will be appreciated as being a very small fraction of the comparable dimension of the wellknown neck type cathode ray tube. There is an additional exaggeration in FIG. 4 in that the diameter of the device would be expected to be greater in respect to the axial depth illustrated in FIG. 4 to accommodate a reasonable size phosphor screen. There is actually no theoretical limit to the screen size which can be provided using the present invention. 1

A reflecting baffle 74 and a plurality of filament wires of which 59 and 60 are typical, constitute a type of flood gun, or area cathode, which more or less uniformly electron illuminates substantially the entire inside surface of the bottom plate 10b. It is from this source that electrons which are gated through the multichannel electron path selector provided by the multichannel array of the device, are derived. The conductive film 37 (see also FIGS. 2 and 3) may be at a relatively fixed potential, so that the gating on the individual holes by the radial and circular conductive strip electrodes is effected by the potential change on those latter electrodes producing potential difference across the plate 10b at the individual hole locations (between gated electrodes and 37).

The element 61 is illustrated as an optional element. It is a state-of-the-art microchannel plate with fixed potentials applied on its opposite faces and secondary emissive material within its microchannels or holes. The construction of this plate is entirely as known in the prior art, and'its tentative inclusion depends upon the degree of electron density desired at the phosphor screen 62. The operation of the multichannel array which provides the switching function (FIG. 3) of the present device, is such that comparatively little secondary emission effect is achieved. The inclusion of the electron multiplier 61 accordingly can provide additional electron densities at 62.

Reference to FIGS. 5 and 6 will provide a clearer idea of the nature of terminal block 54. With a linear scan of the ribbon beam 64, and if the block 54 has an appropriate radius of curvature 67, as depicted in FIG. 6, and the typical conductive extensions 68 and 69, etc., are uniformly spaced, the linearity of the time base scan is preserved. Insulation is provided between adjacent conductive extensions on the face of the terminal block along 67 and throughout its depth to the rear surface 55. At 55 the terminal block 54 would be connected (conductor for conductor) to the extensions along the side flange a inside surface, typically shown as 27, 28 and 29, etc., on FIG. 1.

It will be noted that the ends typically 68 and 69 of the terminal block 54 conductive strips, as well as the surfaces of the extension leads are coated with secondary emissive material 43 and 44. In fact, in FIG. 4, the secondary emissive layers 43 and 44 are both associated with the angular scan. In any event, a secondary emissive collector grid is required for each electron scanner. For the rotating gun 46, a grid 56 partially shown in FIG. 4, is provided. Electrically the said grid is returned to a potential slightly more positive than that of the secondary emission surface with which it is associated during gating. For the scanning terminal block 54 associated with the gun 53 and deflection plates 52, a similar secondary emission collector grid 57 is provided and is returned to a potential slightly more positive than that of the conductive strips of 54 during gating. The operation of these collector 56 and 57 is not unlike that of a suppressor grid in a vacuum tube.

If the display system of the present invention is to be used with a more or less conventional radar type plot, either in PPI or sector-scan form, the slow moving gun 46 can easily be mechanically driven from a magnetic drive 51 by magnetic coupling. to an iron disc 47 directly through the wall of the evacuated enclosure 63.

Referring now to FIG. 7, an alternative scheme for bringing out the conductive extensions of the concentric circular conductive electrodes for the case where the device is to be used with a 360 angular or bearing scan, is shown. The radially extensions are passed underneath the concentric strip electrodes as illustrated and are separated by insulators between the circular strips and the radial extensions at points such as 71, 72 and 73. It will be realized also that in the case of the 360 version, the extension strips along the inside wall of the side flange corresponding to the radially extending conductive strip electrodes must make their way behind the terminal block or between the terminal block surface 55 and the said inside of the side flange wall. In order to avoid interference here, the outer strip extensions may be indented into the wall of Illa adjacent to 55. They could also be overlaid in the vicinity (see FIG. 4) with insulation 58 to separate them from 55.

It will be realized that the radial electrodes of the present invention inherently space out as they extend outwardly, i.e., the are or chord between radials in a function of radial distance. To overcome this, some of the radial electrodes can be shortened so that they extend from the outer perimeter of plate 10b only partly inward.'.Such partial radial electrodes can be interlaced with full radial length electrodes to tend toward equalized display resolution over the entire display screen.

Various other modifications falling within the spirit of the present invention will suggest themselves to those skilled in this art. It should be again emphasized that the techniques of strip construction insulation and hole registration referred to in the hereinbefore cited references may be considered applicable to the structure of the present invention, and the variations contemplated by those references will also be found to be pertinent. Materials suitable for the various elements of the device of the present invention are well known in this art. Actual shape and form factor variations are also obviously possible, once the present invention is well understood.

What is claimed is: I

l. A flat panel cathode ray device for display of information in polar coordinate form, including a phosphor screen within an evacuated envelope, comprising the combination of: 1

an insulating plate having an annular axially extending side flange forming a pan-shaped body, said body being placed within said envelope with its first plate surface on the outside of said pan-shaped body in spaced substantially parallel relationship facing said phosphor screen, said flange extending oppositely away from said phosphor screen;

a plurality of holes arranged in substantially concentric circles and radial lines about a common central location in the plane of said plate, said holes passing through said plate;

a wide area source of flood electrons disposed adjacent a second opposite surface of said plate within said pan-shaped body to direct said flood electrons onto a corresponding wide area of said second surface;

gating potential distributing means controllable to admit substantial electron flow from said source of electrons through substantially only one of said holes at any one time and'sequentially in a polar scanning'pattern, said means including a first set of closely spaced substantially concentric circular conductive strip electrodes each overlapping a discrete circle of said holes and a second set of closely spaced radially extending conductive strip electrodes each overlapping a discrete radial line of said holes, said concentric and radial strips being disposed about said common central location and crossing at positions having a common hole therethrough, said strips all lying in close proximity with said second surface of said plate and having a layer of insulation between said concentric and radial strips, each strip being insulated from all others in both of said sets;

a conductive layer overlapping said holes along said first outside plate surface, said conductive layer and all of said conductive strip electrodes and insulation layer having holes in registration with said plate holes;

means comprising a conductive extension of each strip electrode of said first set along a first predetermined portion of the inside surface of said axial side flange of said pan-shaped body and a conductive extension of each strip electrode of said second set along a second predetermined portion of said axial side flange inside surface, each of said conductive extensions having a layer of secondary emissive material thereon; v

and first and second electron beam generating and scanning means for independently scanning respective electron beams over said first and second conductive extensions corresponding to said first and second sets of conductive strip electrodes respectively, said first beam being directed along said plate to transversely scan said first conductive strip extensions along said axial side flange, said second beam being rotatable and directed radially around said plate from said central area to scan said second conductive strip extensions along said axial side flange, said electrodes being successively gated as said electron beam impinges on said secondary emissive material of each corresponding conductive extension to admit electrons from said source through respective holes in said crossing positions of said strips.

2. Apparatus according to claim 1 in which said conductive extensions of said first set of conductive strip electrodes each connect discretely to corresponding ones of said circular strips and extend generally radially therefrom and axially along said first predetermined portion of the inside surface of said pan'shape body side flange, and said first electron beam scans a first arc corresponding to said first predetermined portion of the inside surface of said side flange at a rate corresponding to the desired rate of scan of said display radially.

3. Apparatus according to claim 2 in which said conductive extensions of said second set of conductive strip electrodes extend substantially axially along said second predetermined portion of the inside surface of said pan-shape body side flange, and said second electron beam scans a second arc so as to scan said second predetermined portion of the said side flange inside surface at a rate corresponding to the desired rate of angular scan of said display:

4. Apparatus according to claim 2 in which said first electron beam generating and scanning means comprises a first source of electrons focused into a concentrated beam narrow in the direction of scan and electrostatic deflection means responsive to an external scan control waveform for scanning through said first arc.

5. Apparatus according to claim 3 in which said second electron beam generating and scanning means comprises a second source of electrons focused into a concentrated beam narrow in the direction of scan and means for mechanically rotating said source over said second are.

6. Apparatus according to claim 5 in which said sec ond source of electrons is mounted on a rotatable centrally positioned shaft aligned axially in said evacuated envelope and magnetic coupling means are attached to said shaft whereby a corresponding magnetic field originating from outside said envelope causes rotation of said magnetic coupling means.

7. Apparatus according to claim 1 including a radial scan terminal block comprising a generally inwardly extending further extension of said conductors of said first set of conductive extensions, said further extensions of said conductors terminating in an arcuate array of strip endings insulated from each other and each containing a coating of secondary emissive material,

vidual conductors of said further extensions along the face of said arcuate array are spaced farther apart than said corresponding extensions along said side flange inside surface to which they are connected. 

1. A flat panel cathode ray device for display of information in polar coordinate form, including a phosphor screen within an evacuated envelope, comprising the combination of: an insulating plate having an annular axially extending side flange forming a pan-shaped body, said body being placed within said envelope with its first plate surface on the outside of said pan-shaped body in spaced substantially parallel rElationship facing said phosphor screen, said flange extending oppositely away from said phosphor screen; a plurality of holes arranged in substantially concentric circles and radial lines about a common central location in the plane of said plate, said holes passing through said plate; a wide area source of flood electrons disposed adjacent a second opposite surface of said plate within said pan-shaped body to direct said flood electrons onto a corresponding wide area of said second surface; gating potential distributing means controllable to admit substantial electron flow from said source of electrons through substantially only one of said holes at any one time and sequentially in a polar scanning pattern, said means including a first set of closely spaced substantially concentric circular conductive strip electrodes each overlapping a discrete circle of said holes and a second set of closely spaced radially extending conductive strip electrodes each overlapping a discrete radial line of said holes, said concentric and radial strips being disposed about said common central location and crossing at positions having a common hole therethrough, said strips all lying in close proximity with said second surface of said plate and having a layer of insulation between said concentric and radial strips, each strip being insulated from all others in both of said sets; a conductive layer overlapping said holes along said first outside plate surface, said conductive layer and all of said conductive strip electrodes and insulation layer having holes in registration with said plate holes; means comprising a conductive extension of each strip electrode of said first set along a first predetermined portion of the inside surface of said axial side flange of said pan-shaped body and a conductive extension of each strip electrode of said second set along a second predetermined portion of said axial side flange inside surface, each of said conductive extensions having a layer of secondary emissive material thereon; and first and second electron beam generating and scanning means for independently scanning respective electron beams over said first and second conductive extensions corresponding to said first and second sets of conductive strip electrodes respectively, said first beam being directed along said plate to transversely scan said first conductive strip extensions along said axial side flange, said second beam being rotatable and directed radially around said plate from said central area to scan said second conductive strip extensions along said axial side flange, said electrodes being successively gated as said electron beam impinges on said secondary emissive material of each corresponding conductive extension to admit electrons from said source through respective holes in said crossing positions of said strips.
 2. Apparatus according to claim 1 in which said conductive extensions of said first set of conductive strip electrodes each connect discretely to corresponding ones of said circular strips and extend generally radially therefrom and axially along said first predetermined portion of the inside surface of said pan-shape body side flange, and said first electron beam scans a first arc corresponding to said first predetermined portion of the inside surface of said side flange at a rate corresponding to the desired rate of scan of said display radially.
 3. Apparatus according to claim 2 in which said conductive extensions of said second set of conductive strip electrodes extend substantially axially along said second predetermined portion of the inside surface of said pan-shape body side flange, and said second electron beam scans a second arc so as to scan said second predetermined portion of the said side flange inside surface at a rate corresponding to the desired rate of angular scan of said display.
 4. Apparatus according to claim 2 in which said first electron beam generating and scanning means comprises a first source of electRons focused into a concentrated beam narrow in the direction of scan and electrostatic deflection means responsive to an external scan control waveform for scanning through said first arc.
 5. Apparatus according to claim 3 in which said second electron beam generating and scanning means comprises a second source of electrons focused into a concentrated beam narrow in the direction of scan and means for mechanically rotating said source over said second arc.
 6. Apparatus according to claim 5 in which said second source of electrons is mounted on a rotatable centrally positioned shaft aligned axially in said evacuated envelope and magnetic coupling means are attached to said shaft whereby a corresponding magnetic field originating from outside said envelope causes rotation of said magnetic coupling means.
 7. Apparatus according to claim 1 including a radial scan terminal block comprising a generally inwardly extending further extension of said conductors of said first set of conductive extensions, said further extensions of said conductors terminating in an arcuate array of strip endings insulated from each other and each containing a coating of secondary emissive material, said strips further defined as being arranged within said arcuate array facing said first electron beam scanning means for scanning and successively gating said corresponding strip electrodes.
 8. Apparatus according to claim 7 in which the individual conductors of said further extensions along the face of said arcuate array are spaced farther apart than said corresponding extensions along said side flange inside surface to which they are connected. 